java中可以通過調用ping命令來判斷網絡是否連接正常

import java.io.BufferedReader;

import java.io.IOException;

import java.io.InputStream;

import java.io.InputStreamReader;

/**

判斷網絡連接狀況. 
@author nagsh 
*/

public class NetState {
public boolean isConnect(){

 boolean connect = false;  
 Runtime runtime = Runtime.getRuntime();  
 Process process;  
 try {  
     process = runtime.exec("ping " + "www.baidu.com");  
     InputStream is = process.getInputStream();   
     InputStreamReader isr = new InputStreamReader(is);   
     BufferedReader br = new BufferedReader(isr);   
     String line = null;   
     StringBuffer sb = new StringBuffer();   
     while ((line = br.readLine()) != null) {   
         sb.append(line);   
     }   
     System.out.println("返回值為:"+sb);    
     is.close();   
     isr.close();   
     br.close();   

     if (null != sb && !sb.toString().equals("")) {   
         String logString = "";   
         if (sb.toString().indexOf("TTL") > 0) {   
             // 網絡暢通    
             connect = true;  
         } else {   
             // 網絡不暢通    
             connect = false;  
         }   
     }   
 } catch (IOException e) {  
     e.printStackTrace();  
 }   
 return connect;  

}
public static void main(String[] args) {

 NetState netState = new NetState();  
 System.out.println(netState.isConnect());  


}


}  </pre>